Impulse unit

ABSTRACT

An impulse unit having a variable torque output and suitable for use in an impulse tool having a housing and a motor, is rotatably mounted in the tool housing and driven by the tool motor. The impulse unit comprises a casing assembly having an impulse cavity therein which is filled with a liquid and a spindle having blade means mounted rotatably with respect to the casing assembly. The blade means carried by the spindle divides the cavity into high and low pressure portions. A regulator valve is provided in the impulse unit to control the torque output of the unit and varies the size of an orifice or passage connecting the high and low pressure portions of the impulse cavity. The cavity, spindle and regulator valve may each be of simple cylindrical configuration.

ilnited States Patent 1 Vana [ 1 Feb. 20, 1973 IMlULSEUNlT [75] Inventor: Vladimir J. Vana, La Grange, Ill.

[73] Assignee: Thor Power Tool Company, Aurora,

22 Filed: April 30, 1971 211 Appl.No.: 138,976

[52] US. Cl ..64/26 [51] Int. Cl ..F16d 3/80 [58] Field of Search ..64/26; 60/545 [56] References Cited UNITED STATES PATENTS 3,116,617 1/1964 Skoog ..64/26 3,210,961 10/1965 Skoog et al ..64/26 Primary Examiner-Edward G. Favors Attorney-Hibben, Noyes & Bicknell {57] ABSTRACT An impulse unit having a variable torque output and suitable for use in an impulse tool having a housing and a motor, is rotatably mounted in the tool housing and driven by the tool motor. The impulse unit comprises a casing assembly having an impulse cavity therein which is filled with a liquid and a spindle having blade means mounted rotatably with respect to the casing assembly. The blade means carried by the spindle divides the cavity into high and low pressure portions. A regulator valve is provided in the impulse unit to control the torque output of the unit and varies the size of an orifice or passage connecting the high and low pressure portions of the impulse cavity. The cavity, spindle and regulator valve may each be of simple cylindrical configuration.

14 Claims, Drawing Figures IMPULSE UNIT This invention relates to impulse units and more particularly to novel and improved impulse units having a variable torque output for use in impulse tools.

In U. S. Pat. No. 3,116,617 an impulse tool is described in which an impulse unit or torque generating mechanism includes a pair of non-impacting or non-striking, relatively rotatable, eccentrically spaced members, one of which is driven by a motor and the other of which is adapted to mount a tool, such as a nut or bolt engaging socket or the like. The space or impulse cavity between the two members is filled with oil or other pressure transmitting liquid, and the internal structure is such that the oil filled space is divided into two portions. As one member rotates relative to the other, the pressure of the oil in the two portions rapidly increases and decreases in a cyclic manner so as to create a series of impulses. These impulses are transmitted through the oil to the driven member.

In such impulse units, various pressure sensing control valves have been provided in order to limit the maximum pressure created in the oil in one portion of the unit and, thus, control the impulse created and the torque output of the tool. Such control valves have springs and valve bodies and depend on these parts opening and closing at a predetermined pressure. Such valves are often complicated and expensive to build and maintain.

Further, the construction of such impulse units, even without such control valves, is difficult and expensive since the internal parts of the impulse units often have shapes that are complicated and difficult to form, e.g., at least a portion of the impulse cavity may be non-circular.

The present invention overcomes the aforementioned disadvantages by providing a novel and improved impulse unit having internal parts, including an impulse cavity, that are easily manufactured. The impulse unit, further has a novel and improved regulator valve which varies the size of an orifice or passage located between high and low pressure portions of the impulse cavity to control the impulse created and the torque output of the unit, and the regulator valve may be easily adjusted to vary the torque output of a tool in which the unit is incorporated.

The primary object of the present invention is to provide a novel and improved impulse unit with a variable torque output.

Another object of the present invention is to provide an impulse unit of the foregoing character having a regulator valve which varies the size of a passage in the unit to control the torque output.

Still another object of the present invention is to provide an impulse unit which has internal parts, including an impulse cavity, which are easily manufactured.

These and other objects of the present invention will become apparent from the accompanying description and following figures of the drawings in which:

FIG. 1 is a sectional view, with a portion shown in elevation, of an impulse tool having an impulse unit embodying the features of the present invention;

FIG. 2 is a front elevational view of the tool shown in FIG. 1, the impulse unit having been slightly rotated from the position in FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1, the impulse unit having been slightly rotated from the position in FIG. 1;

FIG. 4 is an enlarged sectional view taken along the line 4-4 of FIG. 1;

FIG. 5 is an enlarged sectional view taken along the line 5-5 of FIG. 1, and the impulse unit having been slightly rotated from the position in FIG. 1; and

FIG. 6 is an enlarged fragmentary sectional view taken along the line 6-6 of FIG. 1, the impulse unit having been slightly rotated from the position in FIG. 1. Briefly described, an impulse unit embodying features of the present invention may be used in an impulse tool including a housing having a motor mounted therein. The impulse unit is rotatably mounted in the housing and driven by the motor. The impulse unit has an impulse cavity or chamber adapted to be filled with liquid in which a spindle carrying a blade is disposed, the spindle being mounted so as to be rotatable in the cavity of the impulse unit. The blade may be relatively rotated to a position dividing the impulse cavity into high and low pressure portions. A torque regulator valve is provided in the impulse unit and varies the size of a passage or orifice between the high and low pressure portions to control the pressures in the portions whichv create the impulses. Thus the regulator valve controls the impulse transmitted to the blade and spindle. The cavity, regulator valve and spindle of the impulse unit of the present invention may be made of circular cylinders. i

For the sake of convenience, the present inventionis illustrated in connection with a rotary power driven wrench or nut setter, but it will be understood that the principles of the invention which pertain to the torque generating or impulse unit may be utilized to advantage in awide variety of tools.

Referring first to FIG. 1, the tool has a front housing section 21 and a rear housing section 22 with a depending handle portion 23, the front and rear housing sections being detachably connected, as by a plurality of cap screws 24 (FIG. 2). The rear housing section 22 contains a rotary air-actuated motor of a conventional type designated generally at 25, having a rotor or shaft 24' mounted in ball bearings 25'. An air hose 26 may be connected to an air inlet connection 27 at the lower end of the handle portion 23, and the air supply to the motor 25 is controlled by means of a throttle valve assembly mounted in the handle portion 23 and operable by a depressible trigger 29. An impulse unit designated generally at 31, is contained within the front housing section 21, as hereinafter described in greater detail. The impulse unit 31 has a rotatable spindle with an elongated forward shaft portion 32 journaled in an opening 33 in the forward end of the housing section.

21. The outer terminus of the spindle portion 32 is provided with a square end 34 having a depressible detent 35 for detachably mounting a nut or bolt engaging socket or other tool member.

The impulse unit 31 includes a casing assembly, indicated generally at 41, which is adapted to be driven by the air motor 25, and a spindle 42 having the forwardly projecting shaft portion 32 heretofore mentioned.

The casing assembly 41 includes an outer casing 43 having a forward end 44 with two wrench flats 45 (FIG.

2) which may be gripped to facilitate assembling the casing, and an internally threaded rear end portion 46. An internal cylindrical bore 47 concentric within the outer casing 43 forms a concentric portion of an impulse cavity 48, and the remaining or eccentric portion of the cavity 48 is formed by two eccentric cam surfaces 49, hereinafter described. The ends of the impulse cavity 48 are closed by the forward end 44 and a separate rear cap member 51. The forward end 44 has an opening52 to receive the shaft portion 32 of the spindle 42 and an enlarged bore 53 to receive an enlarged diameter portion 55 of the spindle 42. A rotary seal is provided by an O-ring 54 which is mounted in the bore 53 and seals against a shoulder of the casing 43 and the portion 32 of the spindle 42. An annular locking ring or nut 55 threadedly engages the rear end portion 46 and abuts a washer or ring 56 which in turn abuts the rear cap member 51 for retaining the parts of the casing assembly 41 in unitary assembled relation. An O-ring seal 57 is provided between the cap member 51 and the ring 56 and seals against the casing 43. I

The spindle 42 is generally cylindrical in cross-sectional configuration and has a slot in the enlarged central portion 55. A short integral stub shaft portion 63 projects rearwardly from the spindle portion 55 and is journaled in a recess 65 provided in a rearwardly projecting boss portion on the rear cap member 51. The spindle portions 55 and 63 sealingly engage an O-ring seal 64 carried in an enlarged groove formed in the recess 65 of the rear cap member 51. The use of the O- ring 64 prevents pressurized liquid from acting on the rear end of the spindle 42 which otherwise would cause an unbalanced axial force to act on the spindle. The entire spindle 42 is co-axial with the axis of rotation of the casing assembly 41.

The spindle portion 55 has a diametrically extending slot 76 (FIG. 4) therethrough, and a floating blade 77 is mounted in the slot 76 and may divide the impulse cavity 48 into high and low pressure portions. The width of the slot 76 at its ends is substantially equal to the thickness of the blade 77, and the blade may slide in the slot as hereinafter described. The blade 77 is generally rectangular and extends axially in the slot 76 along the spindle portion 55 to the ends of the cavity 48 and radially at opposite sides of the spindle portion 55. The length of the blade 77 is slightly less than the diameter of the cam surfaces 49 so that the blade 77 may rotate freely in the cavity 48 without becoming jammed on the eccentrically located cam surfaces 49. As the blade 77 rotates relative to the impulse cavity 48, it shifts in the slot 76 so that the upper end of the blade, as shown in FIG. 4, always contacts the cam surfaces 49. As best seen in FIG. 4, the outer radially extending ends 80 of the blade 77 are slightly rounded or curved with the edges thereof chamfered or inclined to facilitate rotation of the blade around the cam surfaces 49 and sliding over a body, hereinafter described, should such be necessary.

One of the circumferentially and inwardly extending cylindrical cam surfaces 49, is provided in the forward end 44 of the casing 43, and the other cam surface 49 is provided on a rear flange 82 (FIG. 4) of the casing 43 in abutment with the rear cap member 51. The cam surfaces 49 are located eccentrically with respect to the bore 47 in the casing 43, are of a diameter smaller than that of the bore 47, and are tangent at one point, designated at 83 (FIG. 4), to the bore 47. The axial ends of the blade 77 are supported on and guidedalong the cam surfaces 49, and the blade 77 may be aligned in .temporary sealing engagement with the wallof the cavity 48 at a tangent line or point 83 during relative rotation of the casing assembly 41 and the spindle 42. The eccentricity of the ends of the impulse cavity 48 (bounded by the cam surfaces 49) provides, upon relative rotation of the casing assembly 41 and the spindle 42, an increasing and decreasing volume in the portions of the impulse cavity 48 separated by the blade 77.

The impulse cavity 48 is filled with a suitable oil or other pressure transmitting liquid. The rear cap member 51 has a square drive connection 81 projecting therefrom and engaging a corresponding driving socket connection 82 on the rotor 24' of the air motor 25. Thus, when the air motor 25 is in operation, the casing assembly 41 (comprising 43, 51, 55 and 56) of the impulse unit 31 is rotated and, as described in detail below, fluid pressure impulses are generated and are transmitted through the oil medium to the spindle 42.

To control the torque output of the impulse unit 31 a regulator valve is provided between the two (high and low pressure) portions of the cavity. While the regulator valve could be provided elsewhere in the impulse unit 31 and connected to the cavity 48 by passages, in this instance a regulator valve, designated generally at 85, is located in the cavity 48 directly opposite the tangent point 83 of the impulse cavity 48, and a passage connecting the high and low pressure portions of the cavity is provided through the valve 85 around one of the ends of the blade 77. The regulator valve comprises a body 86 which is movable to vary the size of the orifice or clearance in the passage between the high and low pressure portions of the'cavity. Thus, the oil flow from the high pressure portion to the low pressure portion, the impulse generated, and the torque output, of the unit are controlled by the position of the regulator valve. Preferably, the valve body 86 is cylindrical having a flat relief or cutaway portion 84 less than the length of the blade 77 and is located in the impulse cavity 48 directly opposite the tangent point 83. As seen in FIGS. 1 and 4, the valve body 86 extends radially inwardly beyond the cam surfaces 49 and into the cavity 48 a sufficient distance so that the ends of the valve body 86 at each end of the relief portion 84 contact the blade 77. This distance plus the length of the blade 77 is substantially equal to the diameter of the cam surfaces 49, as shown in FIG. 4. The axis of the regulator valve 85 is parallel to that of the spindle 42.

The cylindrical ends 87 and 87' of the regulator valve body 86 are rotatably mounted in an opening 88 in the forward end 44 of the casing 43 and in a recess 89 in the rear cap 51, respectively. The valve body 86 is held at its outer end by a snap ring 91 which fits in a groove formed in an enlarged portion of the opening 88. A seal ring 88' is provided in the casing 43 to seal the end 87 of the valve body 86.

Means is provided for moving or varying the position of the regulator valve 85 and, in this instance, such means comprises a driven worm gear 93 (FIGS. 1 and 5) located on the forward end of the valve body 86 and a driving worm 94 (FIG. 5) located in a radial bore 95 in the forward end 44 of the casing 43 which is generally perpendicular to and intersects the opening 88. Although other types of adjustment mechanisms could be used, worm type gears are preferred since they are inherently self-locking and, thus, will retain the valve body 86 in adjusted position. A spring 95f at one end abuts the end wall of the bore 95 and at the other end abuts a constriction or shoulder in an axial bore 96 in the worm 94 to hold the latter against a snap ring 96' disposed at the outer end of the bore 95. An Allen socket 97' is provided in the radially outer end of the worm 94.

The worm 94 may be aligned with an opening 97 provided in the front housing 21 and may be rotated with an Allen key 100, as shown in FIG. 5. At the same time, the front end of the valve body 86 which carries index marks H (indicating high torque) and L (indicating low torque) is visible through an opening 101 (FIGS. 2 and 6) in the front housing 21 and through the opening 88. When set in L position, the cutaway portion 84 of the valve body 86 faces toward the cavity 48 to provide a maximum orifice or large passage around one of the ends 80 of the blade 77, and when in H position the solid portion of the valve body 86 faces toward the cavity 48 to close off the passage and provide minimum clearance around one of the ends 80 of the blade 77. The orifice area for flow of oil from the high pressure portion to the low pressure portion of the cavity 48 is variable to any position between the H and L positions by adjustment of the worm 94.

A typical operating cycle of the tool will now be described. As seen in FIG. 4, the casing assembly 41, is being driven in a clockwise direction by the air motor 25, as indicated by the arrow 102. The square end 34 on the forward spindle shaft 32 is assumed to be in engagement through a suitable socket (not shown) with a fastener element (not shown), such as a nut or bolt, which is to be tightened. At the outset of the tightening operation, very little torque resistance is encountered by the spindle and consequently, the coupling provided by the liquid filled impulse cavity 48 is sufficient to cause the blade 77 and the spindle 42 to rotate in unison with the rotating casing assembly 41.

As tightening of the fastener element proceeds and substantial torque resistance is encountered by the rotating spindle 42, the casing assembly 41 begins to rotate relative to and ahead of the spindle 42. At other positions of the blade 77 except that shown in FIG. 4, the cam surfaces 49 position the blade 77 in the impulse cavity 48 so that the oil or other pressure transmitting liquid is free to flow around the ends 80 of the blade, and the pressure throughout the cavity 48 is substantially uniform.

Before the impulse point, which is shown in FIG. 4, the lower end 80 of the blade 77 approaches a momentary dynamic sealing relationship with the regulator valve body 86, and in the same fashion, the upper end 80 of the blade 77 approaches a dynamic sealing relationship with the tangent point 83 of the wall of the cavity 48. At this time, the volume of the portion of the cavity 48 to the right of the blade 77 continues to increase, and the volume of the portion of the cavity to the left of the blade 77 continues to decrease. Also, at this time the blade 77 slides upward in the slot 76 so its lower end 80 will clear the valve body 86.

When in the position of FIG. 4, the blade ends are in dynamic sealing relationship with the valve body 86 I and the cavity wall (at 83), and oil is no longer free to flow around the ends 80 of the blade 77. As a result of this sudden sealing-off of the liquid, a momentary substantially higher liquid pressure is obtained in the left portion of the impulse cavity 48, as indicated by the letter H. In the right portion of the impulse cavity 48, the liquid pressure is substantially lower, as designated by the letter L. This momentary pressure differential between the portions H and L imposes a differential force on the extended upper portion of the blade 77 and thereby causes the spindle 42 to rotate in a clockwise direction to tighten the fastener element. The magnitude of the differential pressure between the cavity portions H and L depends upon the size of the passage connecting the portions which in turn depends upon the position of the regulator valve body 86.

One of the principal advantages of the impulse tool of the present invention is the facility with which such an impulse mechanism lends itself to the control of output torque of the tool. By positioning the cutaway portion 84 of the regulator valve body 86 to face one of the ends 80 of the blade 77, liquid can more freely flow from the portion H at the impulse point and thus a smaller pressure impulse is created. Conversely, by rotating the valve body 86 to substantially close the passage around the end of the blade 77, a greater pressure and impulse are created. Thus, the position of the regulator valve body 86 controls the torque output of the tool and no part of the regulator valve moves during the operation of the unit 31.

As the housing assembly 41 rotates beyond its FIG. 4 position ahead of the spindle 42, the fluid pressure in the impulse cavity 48 is again substantially equalized by reason of the free fluid communication provided by the clearance between the wall of the cavity 48 and the ends 80 of the blade 77. Continued rotation of the easing assembly 41 causes the foregoing cycle to be repeated again during the next one-half revolution with the result that the two impulses per revolution are imparted to the spindle 42 through the medium of the liquid until the desired tightening operation has been achieved. I

To insure that excessive driving torque from the air motor 25 will not be required, a small static leakage between the relatively rotatable casing assembly 41 and the blade 77 is provided. Normal operating clearances of the blade 77 are sufficient to provide the required leakage between the high and low pressure portions of the cavity 48.

To reverse the operation of the tool, the direction of rotation of the air motor 25 is reversed, thereby rotating the casing assembly 41 in the opposite direction and that these functions may be interchanged by minor and obvious modifications of the structure.

Although the invention has been described with particular reference to certain specific structural embodiments thereof, it should be understood that various modifications and equivalent structures may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. In an impulse unit for use in an impulse tool including a housing and a motor, said impulse unit including casing means adapted to be rotatably mounted in said housing and having an impulse cavity therein adapted to be filled with liquid, and spindle means mounted in said cavity for rotation with respect to said casing means, one of said means being adapted to be driven by said motor and the other of said means being adapted to transmit an impulse, said spindle means having a slot completely therethrough and including imperforate blade means slidable through said slot, said blade means being adapted to momentarily divide said cavity into a high pressure portion and a low pressure portion; the improvement comprising a torque regulator valve located in said casing to be momentarily adjacent one end of said blade means, thereby to define a liquid passage between said valve and said one end of said blade means for connecting said high and low pressure portions of said cavity, and means for adjusting the position of said torque regulator valve to vary the size of said liquid passage, whereby the torque output of said impulse unit is controlled by the position of said torque regulator valve.

2. In an impulse unit for use in an impulse tool including a housing and a motor, said impulse unit including casing means adapted to be rotatably mounted in said housing and having an impulse cavity therein adapted to be filled with liquid, and spindle means mounted in said cavity for rotation with respect to said casing means, one of said means being adapted to be driven by said motor and the other of said means being adapted to transmit an impulse, said spindle means having a slot therein and including blade means slidable in said slot, said blade means being adapted to momentarily divide said cavity into a-high pressure portion and a low pressure portion; the improvement comprising a torque regulator valve including a valve body located in said casing means and extending into said cavity and positioned to be momentarily adjacent one end of said blade means to define a liquid passage around said one end of said blade means to connect said high and low pressure portions of said cavity, and means for adjusting the position of said torque regulator valve to vary the size of said liquid passage, whereby the torque output of said impulse unit is controlled by the position of said torque regulator valve.

' 3. The unit of claim 2, wherein said valve body has a generally cylindrical configuration having a cutaway portion defining said liquid passage.

4. The unit of claim 3, wherein said valve body is rotatably mounted in said casing means.

5. The unit of claim 1, wherein said adjusting means comprises driver means mounted in said casing means and accessible from the exterior of said unit, and driven in%said driver means.

means connected to said regulator valve, whereby the position of said regulator valve may be varied by mov- The unit of claim 5, wherein said driver means and said driven means comprise self-locking worm-type gears.

7. The unit of claim 1, wherein said slot in said spindle means extends diametrically therethrough, and said blade means comprises a one piece blade member which extends through said slot.

8. The unit of claim 7, wherein said cavity has an eccentric cylindrical portion and a concentric cylindrical portion, the diameter of said eccentric cylindrical portion being less than the diameter of said concentric cylindrical portion, said eccentric cylindrical portion being tangent to said concentric cylindrical portion,

and said blade member being guided on said eccentric cylindrical portion and having a length less than the diameter of said eccentric cylindrical portion.

9. The unit of claim 8, wherein said regulator valve comprises a valve body mounted in said casing means and extending into said cavity diametrically opposite the tangency of said cylindrical portions, said blade member being of sufficient length to extend in sealing relation between said valve body and the wall of said cavity at said tangency.

10. In an impulse unit for an impulse tool including a housing and a motor, said impulse unit having a casing, a spindle in said casing having a slot therein and slidably carrying a one piece blade in said slot, said impulse unit being adapted to be rotatably mounted in said housing and being adapted to be driven by said motor; the improvement comprising an impulse cavity in said casing, said cavity being adapted to be filled with liquid and being formed by at least one cylindrical cam surface located eccentrically in said casing and a bore located concentrically in said casing, said cam surface being of a diameter smaller than the diameter of said bore and tangent thereto, said one piece blade riding on said cam surface, and means located in said casing opposite the tangency of said cam surface and said bore and extending inwardly from said cam surface into said cavity, said blade being of a length to extend in sealing relation between said means and the tangency of said cam surface and said bore, whereby said blade momentarily divides said cavity into a high pressure portion and a low pressure portion.

11. The unit of claim 10, wherein said means is a regulator valve body for varying the clearance between said valve body and one of the ends of said blade.

12. The unit of claim 1 1, wherein said regulator valve body is cylindrical and has a cutaway portion and is rotatable to vary said clearance.

13. The unit of claim 12, further comprising driver means mounted in said casing and engaging driven means on said valve body, said driver means being accessible from the exterior of said unit.

14. The unit of claim 13, wherein said driver mean and said driven means are self-locking worm-type gears. 

1. In an impulse unit for use in an impulse tool including a housing and a motor, said impulse unit including casing means adapted to be rotatably mounted in said housing and having an impulse cavity therein adapted to be filled with liquid, and spindle means mounted in said cavity for rotation with respect to said casing means, one of said means being adapted to be driven by said motor and the other of said means being adapted to transmit an impulse, said spindle means having a slot completely therethrough and including imperforate blade means slidable through said slot, said blade means being adapted to momentarily divide said cavity into a high pressure portion and a low pressure portion; the improvement comprising a torque regulator valve located in said casing to be momentarily adjacent one end of said blade means, thereby to define a liquid passage between said valve and said one end of said blade means for connecting said high and low pressure portions of said cavity, and means for adjusting the position of said torque regulator valve to vary the size of said liquid passage, whereby the torque output of said impulse unit is controlled by the position of said torque regulator valve.
 1. In an impulse unit for use in an impulse tool including a housing and a motor, said impulse unit including casing means adapted to be rotatably mounted in said housing and having an impulse cavity therein adapted to be filled with liquid, and spindle means mounted in said cavity for rotation with respect to said casing means, one of said means being adapted to be driven by said motor and the other of said means being adapted to transmit an impulse, said spindle means having a slot completely therethrough and including imperforate blade means slidable through said slot, said blade means being adapted to momentarily divide said cavity into a high pressure portion and a low pressure portion; the improvement comprising a torque regulator valve located in said casing to be momentarily adjacent one end of said blade means, thereby to define a liquid passage between said valve and said one end of said blade means for connecting said high and low pressure portions of said cavity, and means for adjusting the position of said torque regulator valve to vary the size of said liquid passage, whereby the torque output of said impulse unit is controlled by the position of said torque regulator valve.
 2. In an impulse unit for use in an impulse tool including a housing and a motor, said impulse unit including casing means adapted to be rotatably mounted in said housing and having an impulse cavity therein adapted to be filled with liquid, and spindle means mounted in said cavity for rotation with respect to said casing means, one of said means being adapted to be driven by said motor and the other of said means being adapted to transmit an impulse, said spindle means having a slot therein and including blade means slidable in said slot, said blade means being adapted to momentarily divide said cavity into a high pressure portion and a low pressure portion; the improvement comprising a torque regulator valve including a valve body located in said casing means and extending into said cavity and positioned to be momentarily adjacent one end of said blade means to define a liquid passage around said one end of said blade means to coNnect said high and low pressure portions of said cavity, and means for adjusting the position of said torque regulator valve to vary the size of said liquid passage, whereby the torque output of said impulse unit is controlled by the position of said torque regulator valve.
 3. The unit of claim 2, wherein said valve body has a generally cylindrical configuration having a cutaway portion defining said liquid passage.
 4. The unit of claim 3, wherein said valve body is rotatably mounted in said casing means.
 5. The unit of claim 1, wherein said adjusting means comprises driver means mounted in said casing means and accessible from the exterior of said unit, and driven means connected to said regulator valve, whereby the position of said regulator valve may be varied by moving said driver means.
 6. The unit of claim 5, wherein said driver means and said driven means comprise self-locking worm-type gears.
 7. The unit of claim 1, wherein said slot in said spindle means extends diametrically therethrough, and said blade means comprises a one piece blade member which extends through said slot.
 8. The unit of claim 7, wherein said cavity has an eccentric cylindrical portion and a concentric cylindrical portion, the diameter of said eccentric cylindrical portion being less than the diameter of said concentric cylindrical portion, said eccentric cylindrical portion being tangent to said concentric cylindrical portion, and said blade member being guided on said eccentric cylindrical portion and having a length less than the diameter of said eccentric cylindrical portion.
 9. The unit of claim 8, wherein said regulator valve comprises a valve body mounted in said casing means and extending into said cavity diametrically opposite the tangency of said cylindrical portions, said blade member being of sufficient length to extend in sealing relation between said valve body and the wall of said cavity at said tangency.
 10. In an impulse unit for an impulse tool including a housing and a motor, said impulse unit having a casing, a spindle in said casing having a slot therein and slidably carrying a one piece blade in said slot, said impulse unit being adapted to be rotatably mounted in said housing and being adapted to be driven by said motor; the improvement comprising an impulse cavity in said casing, said cavity being adapted to be filled with liquid and being formed by at least one cylindrical cam surface located eccentrically in said casing and a bore located concentrically in said casing, said cam surface being of a diameter smaller than the diameter of said bore and tangent thereto, said one piece blade riding on said cam surface, and means located in said casing opposite the tangency of said cam surface and said bore and extending inwardly from said cam surface into said cavity, said blade being of a length to extend in sealing relation between said means and the tangency of said cam surface and said bore, whereby said blade momentarily divides said cavity into a high pressure portion and a low pressure portion.
 11. The unit of claim 10, wherein said means is a regulator valve body for varying the clearance between said valve body and one of the ends of said blade.
 12. The unit of claim 11, wherein said regulator valve body is cylindrical and has a cutaway portion and is rotatable to vary said clearance.
 13. The unit of claim 12, further comprising driver means mounted in said casing and engaging driven means on said valve body, said driver means being accessible from the exterior of said unit. 